The present invention relates to an apparatus for testing the continuity of insulated wires that contain one or more electrical conductors. In particular, the continuity monitor of the present invention is concerned with a testing apparatus that inspects a constantly moving insulated wire as the wire passes an inspection station without sensitivity to the speed of wire movement.
During a continuous process of manufacturing an insulated wire, it is desirable to detect a loss of electrical continuity as the wire passes an inspection station. Preferably, a continuity testing device provides an alarm signal or other signal whenever an incremental length of the wire containing a broken conductor enters the inspection station so that a machine operator can be alerted to the defect, or so that machinery handling the wire can automatically reject and set aside that length of the wire containing a fault. Alternatively, such a signal may be used to mark the wire at the area where a fault has been detected for subsequent processing or removal.
Previously continuity detectors for detecting breaks in insulated wires used eddy current principles with only moderate success. Eddy current detectors are sensitive to the speed of a moving wire, and in a process in which an extended length of wire is manufactured, the speed of movement is sometimes difficult to maintain at a fixed level. Moreover, eddy current detectors require careful adjustment of several controls in order to secure the required sensitivity for detection. Such adjustments are not usually considered to be within the capabilities of a machine operator in an industrial environment.
Accordingly, it is an object of the present invention to provide a continuous continuity monitor for detecting breaks within a moving wire without sensitivity to wire speed. It is a further object of the invention to provide a continuity monitor that is simple in design and which does not require specialized adjustments by the machine operator in order to maintain the sensitivity required for detecting breaks in continuity.